This invention relates to a method and apparatus to heat a forced-air supply with sensible heat recovered from a hot stream of waste flue gases while passing along a chimney of a dwelling or the like by forming an opening in the wall of the chimney to install and operatively support a heat exchanger.
The efficiency of heating systems can be increased by a greater utilization of heat produced by burning fuel within the dwelling. In dwellings, particularly family dwellings, flue gases are generated from one or more sources. It is common practice to heat a family dwelling by a forced-air heating system including a furnace wherein fuel such as oil, liquid gas or natural gas is burned within a chamber that is coupled to a flue provided by a chimney for discharging hot waste gases of combustion into the atomsphere. Water heaters using heat from the combustion of fuel also discharge waste gases into the flue provided by the chimney. It is also common practice, with increasing popularity, to burn fuel in a fireplace and thereby provide heat for one or more rooms of a dwelling. This hot waste gas is carried from the dwelling by the flue of a chimney. The sensible heat of the gases which is exhausted by the chimney to the atmosphere represents a substantial loss to the heating efficiency and the required use of fuel and ever-increasing costs.
The present invention seeks to recover sensible heat from waste fuel gases while conducted by a flue in a manner that is not detrimental to the operation of the flue. The method and apparatus is particularly designed for use with existing flues by embodying a construction of parts that, while a part thereof extending into the flue-conducting space of the chimney, the cross-sectional area of the chimney is not reduced.